Britain said it was "concerned" by reports that North Korea conducted a missile test today, which the US Defence Department said blew up almost immediately.
The Foreign Office in London said it was "concerned by reports of a missile test by North Korea" and was "monitoring the situation closely".
The failed missile came the day after Pyongyang publicly showcased its ballistic arsenal at a giant military parade.
British Foreign Secretary Boris Johnson earlier urged North Korea to abide by UN resolutions and stop its pursuit of nuclear weapons.
"We have been here before but continue to monitor the situation carefully," Johnson said in a statement.
"We stand alongside our international partners in making clear that North Korea must adhere to UN resolutions designed to secure peace and stability in the region and stop its pursuit of nuclear weapons."
The nuclear-armed state is under United Nations sanctions over its weapons programmes.
North Korea's weapons of war rolled through Pyongyang on yesterday and a senior figure in the regime said it could "beat down enemies with the power of nuclear justice", as leader Kim Jong-Un mounted a spectacular show of strength.
Ostensibly yesterday's event was to mark the 105th anniversary of the North's founder Kim Il-Sung's birth.
But it was also intended to send an unmistakable message to Washington about the isolated country's military might.
Tensions over North Korea's nuclear ambitions are stretched to the limit, with US President Donald Trump deploying an aircraft carrier battle group to the region.